Associations of Physical Activity and Cardiorespiratory Fitness With Incident Chronic Kidney Disease in a Korean Population

Objective: This large cohort study aimed to examine the overall associations of physical activity (PA) and estimated cardiorespiratory fitness (eCRF) with incident chronic kidney disease (CKD). Methods: This study included a total of 274,292 participants (mean age, 37.9 ± 8.0 years; 41% women) using data collected from the Kangbuk Samsung Health Study. The participants were categorized into three groups: PA (inactive, insufficiently active, and active) and eCRF(low, middle, high). Furthermore, subgroup analyses were conducted to examine the differences in the risks of CKD incidence by age and sex. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). Results: A total of 932 participants (0.34%) developed CKD. PA level was not associated with CKD risk in the overall cohort. However, younger participants (<45 years) showed lower CKD risks, with HRs of 0.53 (95% CI: 0.36-0.79) and 0.73 (95% CI: 0.53-1.00) for insufficiently active and active individuals, respectively. Similarly, men exhibited reduced CKD risks, with HRs of 0.77 (95% CI: 0.59-1.00) and 0.81 (95% CI: 0.66-1.00) in these groups. Additionally, those in the high eCRF group had a 20% reduced CKD risk (HR, 0.80; 95% CI: 0.67-0.96) compared to the low eCRF group. Conclusions: The associations between PA or eCRF and incident CKD showed differences according to age and sex.